Wyoming officials issued an unprecedented health alert Wednesday in a rural gas-drilling area for a buildup of ozone — usually a summertime air pollutant in urban areas.

The Pinedale area had high ozone readings a week after the U.S. Environmental Protection Agency criticized the federal Bureau of Land Management for planning thousands of new gas wells in the area without adequate air-quality protection.

“This should be a wake-up call for the Bureau of Land Management,” said Linda Baker, director of the Upper Green River Valley Coalition. “What’s going to happen to our air when we have 4,400 . . . additional wells, as the BLM proposes?”

In Colorado, state regulators are targeting gas wells as a major contributor to the Denver metro area’s troublesome ozone levels and are considering new restrictions on equipment and operations.

The Wyoming Department of Environmental Quality issued its first health alert for the Pinedale area, in Sublette County, after recording ozone levels nearly 50 percent higher than the federal health standard.

Ground-level ozone — a component of urban smog formed through a mixture of sunlight, heat and gases from combustion — can impair breathing.

Groups particularly at-risk include infants, the elderly and those with respiratory problems.

“We wanted to let those susceptible know that today might not be the best day to run a marathon,” said Dave Finley, administrator of Wyoming’s air-quality division.

Gas producers in the area were asked to limit unnecessary activities during the next several days when high ozone levels are forecast, said Andrew Bremner, director of government affairs for the Independent Petroleum Association of Mountain States.

“We are looking for ways to further lessen our emissions during this time,” he said.

Industry seeks a solution

Industry officials say that operational activity is no different than last year and that they are working on a solution in their plans with the BLM.

Baker and other critics, however, say the rapid increase in gas exploration has occurred without adequate environmental safeguards.

“Our air may be like Los Angeles before long,” she said. “Our coalition has been saying for the past six years that we need to slow the pace of development.”

State officials first recognized a buildup of wintertime ozone around Pinedale in 2005 and launched a study.

That study found that ozone formed on days when strong temperature inversions, light winds and bright sunlight reflecting off the snowpack trapped the nitrous oxides and volatile organic compounds from engines and escaping gas, Finley said.

“If one of them goes away — for example, if we had cloud cover, or if we had winds pick up — we wouldn’t have an ozone problem,” he said.

Ozone followed drill boom

Finley said the ozone buildup has corresponded with the drilling boom on the nearby Jonah and Pinedale Anticline natural-gas fields.

“They’re a big source . . . in that area,” he said. “There is an awful lot of drilling, so there are a lot of engine emissions from drill rigs, lots of truck traffic, lots of handling of natural gas.”

Last week, EPA regional administrator Robbie Roberts admonished the BLM for its plan to increase natural-gas production in the area without implementing adequate environmental protections.

“The impacts are of sufficient magnitude that the proposed action should not proceed as proposed,” he wrote in a letter declaring the plan “environmentally unsatisfactory.”

The 7,800-acre Winter Valley Fire in Moffat County was 100 percent contained Tuesday as visible smoke from interior islands showed minimal creeping behavior, according to the Bureau of Land Management.